Metal petroleum sulfonate recovery

ABSTRACT

Metal petroleum sulfonates are recovered from commercial oilcontaining concentrates by diluting the concentrate with a volatilizable hydrocarbon diluent, and extracting the mixture with a lower alcohol such as methanol or ethanol. The metal petroleum sulfonate, which is useful as a detergent additive for lubricating oils, is recovered from the alcohol phase as a substantially dry powder.

United States Patent Walters METAL PETROLEUM SULFONATE RECOVERY [72] Inventor: Harold C. Walters, Bartlesville, Okla. [73] Assignee: Phillips Petroleum Company [22] Filed: Nov. 9, 1967 [211 App]. NO-Z 681,889

s2 U.S. c1. ..260/504 A 511 1m. 01 ..C07c 13/00 [58] Field 61 Search ..260/504 8, 504 A, 504, 504 R [56] References Cited UNITED STATES PATENTS 1,087,888 2/1914 Petroff ..260/504 R 1,493.1 11 5/1924 Divine.... ..260/504 R 1,960,828 5/1934 Reddish et al. .....260/159 2,158,680 5/1939 116131111180 ..260/504 2,381,708 8/1945 Amott ..260/504 2,108,755 2/1938 MCAIIlSter.... ..260/99. 12 3,135,693 6/1964 Whitney 6131.... ..260/504 3,476,800 1 1/1969 Cease ..260/505 1151 3,666,795 1 1 May 30, 1972 2,909,563 10/ I959 Whitney ..260/504 2,884,445 4/ I959 Axe et a] ..260/504 FOREIGN PATENTS OR APPLICATIONS 468,781 10/ l 950 Canada ..260/504 OTHER PUBLICATIONS Guise and Stevens, Chemical Technology of Petroleum, Mc- Graw-Hill (NY. 1960) Primary Examiner-Leon Zitver Assistant Examiner-L. B. De Crescente Attorney-Young and Quigg [57] ABSTRACT Metal petroleum sulfonates are recovered from commercial oil-containing concentrates by diluting the concentrate with a volatilizable hydrocarbon diluent, and extracting the mixture with a lower alcohol such as methanol or ethanol. The metal petroleum sulfonate, which is useful as a detergent additive for lubricating oils, is recovered from the alcohol phase as a substantially dry powder.

7 Claims, No Drawings BACKGROUND OF THE INVENTION This invention relates to metal organic sulfonates. In accordance with another aspect, this invention relates to an improved process for the recovery of metal petroleum sulfonates from oil concentrates containing same by a process comprising dilution followed by extraction. In accordance with a further aspect, this invention relates to a recovery process for recovery of substantially oil-free metal petroleum sulfonates from oil-containing concentrates by diluting the concentrate with a volatilizable diluent, and then extracting the mixture with a lower alcohol whereby the metal petroleum sulfonate is recovered from the alcohol.

Oil soluble alkaline earth metal salts of petroleum sulfonates are widely known and widely used materials. They have particular application as additives in lubricating oils. An example of such a material is the calcium petroleum sulfonate whose preparation is described in US. Pat. No. 3,135,693, William B. Whitney et al. In general, the sulfonate salts are prepared by sulfonating a suitable petroleum stock such as a high viscosity solvent refined Mid-Continent oil. The resulting sulfonic acid mixture is neutralized with a base, such as lime, and the metal sulfonate salt is generally utilized in the form of a concentrate in its residual unsulfonated oil from which it is ordinarily difficult to separate. For example, the active calcium petroleum sulfonate referred to in the above-mentioned patent generally exists as about a 50 weight percent solution in similar unsulfonated oil.

Concentrates of the oil soluble sulfonate salts are very convenient in most cases and, in many cases, the unsulfonated portion of the concentrate actually provides additional benefits. However, there are occasions when it would be highly desirable to obtain and to use a metal sulfonate which has been isolated from its carrier oil. Such a product, for ex ample, would provide significant savings in shipping because of its reduced total weight and volume.

Accordingly, an object of this invention is to provide a process for recovering oil-soluble metal petroleum sulfonates from oil solutions containing same.

Another object of this invention is to provide a process for recovering a substantially oil-free metal petroleum sulfonate from commercial oiLcontaining concentrates containing same.

A further object of this invention is to provide a process for recovering metal petroleum sulfonates from its concentrate in residual unsulfonated oil in a practical and simplified manner.

Other objects, aspects, and the several advantages of and features of this invention will become apparent to those skilled in the art from the specification and appended claims.

SUMMARY OF INVENTION In accordance with this invention, it has now been found that the principal active ingredient, namely, the metal sulfonate salt, can be isolated or recovered from its concentrate in residual unsulfonated oil by a process comprising dilution of a concentrate with a volatilizable hydrocarbon solvent and extraction with a lower alcohol.

The extraction of the invention differs from other previously used extraction techniques in that it utilizes the lower alcohols as the extracting agents and in that it extracts the sulfonate salt from a concentrate rather than extracting the oil from the concentrate.

In accordance with one embodiment, the invention comprises a process of diluting the sulfonate-containing concentrate with a suitable volatile solvent, preferably a volatilizable hydrocarbon diluent, and then extracting, preferably repeatedly, the diluted concentrate with an alcohol such as methanol or ethanol.

Extraction of the diluted concentrate with the alcohol results in a alcohol-containing extract phase containing the sulfonate salt and a rafi'mate oil phase comprising the hydrocarbon diluent, the residual unsulfonated oil and a depleted quantity of the sulfonate salt. These phases are subsequently separated from each other.

The extract phase comprising alcohol and sulfonate salt can be subjected to evaporation or other treatment to remove the alcohol and leave the sulfonate salt substantially as a dry powder. Similarly, the raffinate phase of hydrocarbon diluent, oil, and some sulfonate salt can be subjected to further recovery for removal of the hydrocarbon diluent for reuse in the process as desired.

DESCRIPTION OF PREFERRED EMBODIMENT The metal sulfonate salts to which the present invention applies include any conventional alkaline earth metal petroleum sulfonate prepared from any useful petroleum-derived stock by any conventional process which produces a concentrate in an oil carrier. The process of Whitney et al. is particularly applicable. Overbased concentrates are also applicable, but the sulfonate becomes separated from the overbasing agent. The alkaline earth metals are preferred, and barium, and more especially calcium, are specifically preferred in the practice of this invention.

As is known in the art, and particularly as set forth in said Whitney et al. patent, the metal petroleum sulfonates in oil treated according to the invention are obtained by sulfonating a highly refined, high molecular weight petroleum fraction with liquid SO dissolved in an inorganic solvent, neutralizing the reaction mixture with the carbonate, oxide or hydroxide of a metal, heat treating the neutralization reaction mixture to stabilize the sulfonate with respect to ferrous corrosion, expelling moisture, removing unreacted inorganic salts and solids, and recovering a mixture of metal sulfonate and product oil, e.g., SO treated bright stock, as the product. A mixture of metal sulfonate and product oil as described above is treated in accordance with the invention.

The solvents which are suitable for diluting the sulfonatecontaining concentrate are preferably the lower hydrocarbons having up to about 12 carbon atoms which can be easily removed from the system by distillation and recycled. Paraffins such as n-pentane, hexanes, octanes, decanes, and the like can be used. Aromatics such as benzene, toluene, xylenes, can also be used. The amount of solvent used for the solution will range from about 0.1 to about 3, preferably 1 to about 2, parts by weight of solvent for each by weight of the concentrate.

The lower alcohols which can be used as the extracting agents of this invention are methanol and ethanol with methanol being presently preferred. The quantity of the alcohol used will be such that the ratio of hydrocarbon diluent to alcohol will be in the range of 0.5 to about 10, preferably 1 to about 2, parts of diluent per part of alcohol by weight. When aromatic solvents, such as benzene, are used to carry out the initial dilution, the diluent to alcohol ratio preferably does not exceed 2. Greater benzene usage gives good product recovery, but the product is less dry.

According to the process of the invention, the sulfonatecontaining concentrate is first contacted with the hydrocarbon diluent under any suitable conditions of temperature and pressure such that the contacting takes place in substantially the liquid state. Room temperature and atmospheric pressure have been found convenient for this contact. The diluted sulfonate-containing concentrate is then contacted with the alcohol extracting agent under similar conditions of temperature and pressure. Any conventional contacting device or procedure can be used which provides the adequate mixing of liquids such as that required for conventional liquid-liquid extraction procedures. Repeated extraction or multiple stage extraction units are preferred for greater product recovery. It is presently believed that some fractionation occurs and the initial extracts contain sulfonate salts of lower molecular weight,

When the concentrate, diluent, and alcohol have been adequately contacted, the mixture is allowed to settle into phases. The settling period can range from about 1 minute to several hours, but is preferably about 15 minutes. The alcohol phase containing the sulfonate salt will generally be the upper phase, except when relatively large amounts of relatively low density paraffinic diluent are used in the process.

After the settling period, the alcohol phase is decanted and the alcohol removed by evaporation to yield the dry metal sulfonate salt which appears to be hygroscopic. The evaporated methanol can be condensed and recycled to the extraction process. When the concentrate has been sufficiently depleted in the sulfonate salt, the diluent can also be removed by evaporation or distillation and recycled for use in the separation process.

Although the extract will contain most of the alcohol and the ralfinate will contain most of the hydrocarbon solvent, it is readily understood that such a division is not complete and each phase will contain measurable but harmless amounts of the opposite solvent.

The evaporation of the alcohol phase to recover the sulfonate can be carried out in any conventional apparatus using any conventional technique. In some cases, during the alcohol evaporation stage, particularly when aromatic solvents such as benzene are used for the initial dilution, an oil phase will separate out. Removal of this intermediate oil phase will improve the dryness of the recovered sulfonate product.

The invention can be further demonstrated by the following example:

EXAMPLE A IOO-gram quantity of a commercial calcium petroleum sulfonate which contained about 50 weight percent of the solid sulfonate salt in a heavy residual oil was charged into a 600 ml. beaker and diluted with 150 g. of benzene. After the dilution, 100 g. of methanol was added and the mixture was agitated well with a stirring rod.

After about a 15 minute settling period, the upper alcoholic phase was drawn off and evaporated on a hot plate. The evaporation proceeded at a temperature of about 138 F. (a methanol-benzene azeotrope) until about 40 50 ml. of the extract remained. At this time the temperature rose to about 140 F. and a lower liquid phase was visible in the evaporation vessel. The two extract phases were separated and the evaporation of each was continued, the temperature reaching about l47 F. before dryness. After evaporation on a hot plate the drying was completed in an oven at 200 F. for 1 hour. A total of 5 grams of hygroscopic product was obtained. The portion of the product obtained from the phase which settled out during the evaporation was a little tacky.

Several other additional tests were carried out using different diluents or different diluent to alcohol ratios. In addition, one test was made in which the extraction was attempted without the presence of a diluent. The results of these tests as well as the example shown above are found in the following table.

g. Isolated Product g. Sulfonate test concentrate g. Diluent g. Alcohol 100 Benzene 150 Benzene 3 I00 200 Benzene Methanol 8.6 tacky solid 4 100 None 100 Methanol 0.15 solid 5 100 107 n-pentane 100 Methanol 1.3 dry powder 6 100 n-pentane 100 Methanol 1.3 dry powder 7 100 20-0 n-pentane I00 Methanol 1.3 dry powder 8 100 Obased I00 n-pentane 100 Methanol 1.0 dry solids Very diflicult to obtain initial phase separation.

The data in the table above show that the invention process is capable of isolating a dry solid calcium petroleum salt which is essentially free of all visible oil. The data also show that both a hydrocarbon diluent and an alcohol must be present for a successful and convenient extraction. The use of benzene as a diluent results in greater recovery of product for extraction per extraction stage, but the product apparently contains traces of residual oil because it is a tacky solid.

1 claim:

1. A process for the recovery of oil-soluble alkaline earth metal petroleum sulfonates from oil-containing concentrates said sulfonates obtained by neutralizing a sulfonated highly refined, high molecular weight petroleum fraction and said concentrates comprising oil-soluble alkaline earth metal petroleum sulfonates and unreacted or unsulfonated oil containing same which comprises (a) diluting said concentrate with a volatilizable hydrocarbon solvent containing up to about 12 carbon atoms selected from the group consisting of paraffins and aromatics, (b) extracting said sulfonate from said diluted concentrate with methanol or ethanol to form an extract phase comprising alcohol and alkaline earth metal petroleum sulfonate and a raffinate phase comprising oil and hydrocarbon solvent and separating said phases and (c) recovering the oil-soluble, alkaline earth metal petroleum sulfonates from said extract phase.

2. A process according to claim 1 wherein said concentrate is unsulfonated oil associated with said sulfonate and said extracting is repeated a number of times for greater sulfonate product recovery.

3. A process according to claim 1 wherein the concentrate of hydrocarbon solvent and alcohol mixture of step (b) is allowed to settle into phases and the alcohol phase containing the sulfonate is subjected to evaporation of the alcohol to yield a substantially dry alkaline earth metal sulfonate powder as product.

4. A process according to claim I wherein said alkaline earth metal petroleum sulfonate is calcium petroleum sulfonate, said hydrocarbon solvent is benzene or n-pentane, and said alcohol is methanol.

5. A process according to claim 1 wherein the amount of hydrocarbon solvent used ranges from about 0.1 to about 3 parts by weight of hydrocarbon solvent for each weight of the concentrate.

6. A process according to claim 1 wherein the amount of alcohol employed will amount to one weight part of alcohol per 0.5 to about 10 parts of hydrocarbon diluent.

7. A process according to claim 3 wherein the alcohol recovered is recycled to step (b) and the hydrocarbon solvent is recovered from the rafiinate phase and recycled to step (a). 

2. A process according to claim 1 wherein said concentrate is unsulfonated oil associated with said sulfonate and said extracting is repeated a number of times for greater sulfonate product recovery.
 3. A process according to claim 1 wherein the concentrate of hydrocarbon solvent and alcohol mixture of step (b) is allowed to settle into phases and the alcohol phase containing the sulfonate is subjected to evaporation of the alcohol to yield a substantially dry alkaline earth metal sulfonate powder as product.
 4. A process according to claim 1 wherein said alkaline earth metal petroleum sulfonate is calcium petroleum sulfonate, said hydrocarbon solvent is benzene or n-pentane, and said alcohol is methanol.
 5. A process according to claim 1 wherein the amount of hydrocarbon solvent used ranges from about 0.1 to about 3 parts by weight of hydrocarbon solvent for each weight of the concentrate.
 6. A process according to claim 1 wherein the amount of alcohol employed will amount to one weight part of alcohol per 0.5 to about 10 parts of hydrocarbon diluent.
 7. A process according to claim 3 wherein the alcohol recovered is recycled to step (b) anD the hydrocarbon solvent is recovered from the raffinate phase and recycled to step (a). 